The field of orthodontics is well developed. Using conventional brackets, wires and the like, and based upon the nature of a patient's misaligned teeth, a dental professional can determine a pathway for applying appropriate forces to move teeth into better alignment. As the teeth are moved in such conventional procedures, they will often be blocked by other teeth. Because of the initial misalignment, it is often not simply a matter of moving, or repositioning, a tooth in one direction to correct its position. Rather, the treatment plan most often must account for physical contact between teeth as they move.
There have been developed methods of correcting the position of misaligned teeth using dental trays fabricated in a manner that a given tray will itself exert a force upon the misaligned teeth to cause movement. These include for example, the Invisalign® trays from Align Technology, Inc. of Santa Clara, Calif. Often these alignment trays are fabricated from a clear plastic material, and are provided in a series such that each succeeding tray moves the teeth more or differently than the previous tray, in an incremental fashion so as to effect the prescribed treatment plan. Each tray therefore, will move certain teeth from a starting or “before” position to a selected ending or “after” position. The “after” position is based solely upon the nature of the immediately previous “before” position. Further, the shape and force exerted by each successive aligner tray in the treatment process of the conventional system is based only upon the nature of where the previous tray left off in the moving of the teeth. There may be some target goal in mind as to where the dental professional wants to ultimately move the teeth, but until the very end of the patient's treatment procedure, this final position and the initial starting position do not affect the incremental or intermediate treatment steps. That is, the conventional system can be said to be “closed.”
Because of this, it has often been necessary therefore, to apply excessive stripping to teeth in order to allow them to move in the approximate direction desired. The results of excessive stripping are often not aesthetically appealing or even healthy for the stripped teeth. While the conventional procedures will move teeth, they do not permit the teeth to move in their more natural or open pathways.
It would be advantageous therefore, for an alignment tray to be fabricated and used in a manner that allows for the open or natural movement of teeth. That is, the tray and the resulting procedure should more readily and appropriately accommodate the variables to tooth movement including not only the initial misaligned position of a given tooth and the final desired position, but also the physical interaction that exists between teeth or that will occur as the teeth move, the variable nature of the underlying bone structure and the like. Heretofore, conventional orthodontic aligner trays have not allowed for this type of natural tooth movement in orthodontic procedures.
Another practice used by orthodontists involves altering a polymeric shell-type aligner beyond its original as-formed configuration. Typically the interior, tooth-contacting surfaces of tooth-accommodating compartments are formed in an aligner. The inside surface of any one compartment completely surrounds and is in intimate contact with its tooth when the appliance is seated in position. For forces such as those created through the installation of a single bump in an interior wall of an aligner to be effective in moving the tooth, the interior wall on the opposite side of the compartment must be relieved or removed to allow the tooth to move in that direction. The tooth will not move unless obstacles have been cleared and free space is provided for that tooth to move into. To handle such situations, orthodontists may alter aligners by cutting away material or blocking out portions of a tooth model, to create free space for a tooth to move into. Free space or windows are created by trimming away aligner material in the direction of desired tooth movement. A window in an aligner will be created for example on the labial side of a tooth if the treatment plan requires that a bump be formed on the lingual side. It would be advantageous as well to provide an aligner tray with tooth compartments that include space into which the targeted teeth may move, without having to manually cut away tray material or block out portions of a tooth model when forming the tray.